The invention relates to thermal management in instrumentation and more particularly it relates to temperature control of a near-infrared analyzer.
Thermal management in instrument packaging has always been an important design consideration. Internal temperature control of near-infrared (NIR) analyzers is essential for measurement precision. More particularly, NIR spectrophotometers can be affected by temperature variations as little as 2 to 4 degrees C., which cause shifting of optimal wavelengths, and the addition of error in the measurement.
The typical process spectrophotometer is controlled within a band of temperature by utilization of an on-off type control strategy. In the "on" state, a condenser or other device is turned on to remove heat build-up from within the spectrophotometer enclosure. The condenser or other device remains "on" until a low temperature limit is reached and then the condenser is turned "off." The temperature in the spectrophotometer enclosure rises from the heat generated by the electronics and/or the external environment until a second temperature limit is reached, which causes the condenser or other device to be turned "on" again. This on/off temperature control approach commonly allows the internal temperature to cycle 2-4 C. degrees.